Electromechanical power converter

ABSTRACT

The miniaturization of electrodynamic converters causes and over-proportional reduction in power conversion density. The particular functional arrangement of the elements inside the power converter makes it possible to involve nearly the entire volume in the power conversion process. Flux concentration and multiple functions of different components permit and increase in the power conversion density in comparison to conventional miniaturizable converters. By rotating the toothed element wheel ( 9 ), an alternating magnetic flux from the permanent magnet elements ( 14 ) of the alternating axially polarized magnet ring ( 13 ) is conducted through the holed pin ( 1 ) via different magnet flux elements ( 21 ). Axially/radially oriented magnetic circuits ( 19 ) surround a flat coil ( 11 ) resting on the holed pin ( 1 ) and exert an induction action there. The power converter has a simple and robust design as well as a high power conversion density with regard to volume, and can be produced using conventional manufacturing techniques. In addition, very small sizes exhibiting a high power density can be realized.

Miniaturization of electrodynamic converters requires attention tospecific aspects. The concepts and methods for producing largerelectrical machines cannot be readily applied to machines having verysmall dimensions.

Frequently, air gap coils are used for miniaturized motors. The currentconductors required for generating the forces are hereby arranged in theair gap between the flux-conducting elements of the magnetic circuits.U.S. Pat. No. 3,796,039; CH 570 648; JP 01-009372; DE 420595 C2; and DE19902371 A1 describe examples for using air gap coils. Regardless ifwire wound coils or coils produced by micro-mechanical methods are used,such coils disadvantageously require a relatively large air gap due totheir spatial dimensions, which reduces the effective magnetic fluxdensity and hence the power density of the energy converter. These typesof converters require a complex manufacturing process, in particularwith respect to the production of the coil arrangement.

Single-phase stepper motors have a simpler deign, in particular forminiaturized converters. U.S. Pat. No. 4,277,704 describes one suchembodiment with an asymmetric configuration, which independent of thenumber of poles uses a single concentric coil which is placed on aone-piece laminated yoke. The flux through the permanent-magnet rotor isguided by pole nose portions. One disadvantage is poor volumeutilization, low efficiency, and the difficulty of integrating thedevice in systems due to the shape of the energy converter. This type ofelectrodynamic converters is used in U.S. Pat. No. 6,120,177 as a drivefor watches and as a generator for generating electric energy frommechanical motion energy.

The power density can be increased through flux concentration bysoft-magnetic elements. DE 3135385 C2 describes an exemplary use of alaminated stator which forms pole arms and simultaneously reduces theeffective air gap. The pole arms support coils. The rotor is configuredas an external rotor and has a magnet ring which is polarizedalternatingly in the radial direction with a cylindrical flux return.One disadvantage is the large moment of inertia. The distributed coilsimpede miniaturization and increase the manufacturing complexity.

Flux concentration and improved miniaturization are common in convertersof the claw-pole type, as illustrated, for example, in DE 69613207 T2and U.S. Pat. No. 4,644,246. These have alternatingly toothed statoryokes disposed about a ring coil, and a number of magnetized permanentmagnets in the rotor, with the number of permanent magnets depending onthe number of stator poles. Stator assemblies with a large number ofpoles can be implemented by using a single coil. The large stray fluxbetween the alternatingly bent-over stator teeth reduces the powerdensity and efficiency of such converters.

DE 2560231 C2 discloses a DC motor with an integrated tachometergenerator for controlling the rotation speed. The tachometer generatorincludes a rotor, a soft-magnetic flux return element, a ring magnet, aring coil in the flux return element, and a compensation coil outsidethe flux return element. The rotor of the tachometer generator isattached to the motor shaft and includes a soft-magnetic disk with teethdisposed along the circumference, a soft-magnetic bushing and a catch.The alternatingly radially magnetized ring magnet is embedded in theflux return element. Identically named poles of the magnet are arrangedin radial opposition to the rotor teeth. The magnetic flux which changesduring the rotation is chained with the measurement coil and induces inthe measurement coil a voltage proportional to the rotation speed. Theflux is guided from the ring magnet via the flux return element, via aninternal radial air gap to the bushing, via the toothed disk and via anouter radial air gap back to the magnet. The air gaps have to be quitelarge because of potential installation tolerances of the selectedconfiguration. The radial air gap on the bushing preventsminiaturization of the design. The integration of an independent rotorsupport also becomes more difficult. Moreover, the miniaturization cansignificantly increase the stray flux, and the simultaneous action ofthe magnetic forces on all teeth due to the miniaturization can producea significant latching torque. Because the output power of tachometergenerators is intentionally quite small and sufficient design space isavailable, assemblies according to DE 2560231 C2 can be readilyemployed.

All the aforedescribed examples have only limited applicability forrealizing small design sizes with a high-power density.

It is an object of the invention to provide an electromechanical energyconverter with a stationary assembly and a high torque for energyconversion, which provides a high energy conversion density already at alow rotation speed, which has a simple and robust construction, andwhich can be easily manufactured in small sizes.

The object of the invention is solved by an electromechanical energyconverter according to claim 1.

The invention relates to an energy converter which is suitable forconverting mechanical energy into electrical energy as well as forconverting electrical energy into mechanical energy, wherein themechanical energy exchange to the environment is accomplished via arotor according to claim 1 and the electric energy exchange to theenvironmental is accomplished via the terminals of a flat coil accordingto claim 1.

The magnetic flux change necessary for energy conversion in the energyconverter of claim 1 and the cooperation with a coil follows essentiallythe principle established in DE 2560231 C2. However, the design of anenergy converter according to claim 1 is has a considerably moreversatile design, is considerably more compact, smaller, and has asignificantly higher performance and can be implemented as a stand-alonedevice. Important, in particular for miniaturization, are the designparticulars in the regions of the energy converter near the center andin the axially adjoining regions. Accordingly, a core zone according toclaim 1 is defined as the space, which is included in the axialprojection of the inside diameter of the flat coil.

In the context of this application, a flat coil is to be understood as acoil where the ratio of coil height to outer diameter of the coil isless than 1. Advantageously, with the stationary arrangement of the flatcoil according to claim 1, the flat coil can be contacted by a fixedwiring arrangement, thus obviating the need for a brush assembly. Theconcentric arrangement about the rotation axis of the rotor, whichsimultaneously represents a system axis for the energy converter, andthe design as a flat coil result in a rotationally symmetric, preferablyflat and space-efficient design of the energy converter.

The magnetic flux element and permanent magnet elements arranged aboutthe flat coil according to claim 1 completely surround the flat coilexcept for functionally required air gaps, whereby the term “air gap”used herein generally refers to a magnetically inactive space andtherefore also includes regions that are filled with non-magneticsolids. The air gaps are always arranged concentrically about therotation axis of the energy converter and will therefore be referred toas annular air gaps. With complete pole coverage, the magnetic fluxelements form axially-radially oriented magnetic circuits. The fieldlines emanating from magnetic poles having the same pole designationthen extend in a closed axial-radial path about and through the flatcoil, i.e., on the end faces in a radial direction, and outside andthrough the center in an axial direction, thereby completely surroundingall coil windings.

Advantageously, with the electromechanical converter according to claim1, in addition to the flat coil, the permanent magnet elements are alsostationary and arranged with rotation symmetry to form a magnet ring.The permanent magnet elements of the magnet ring can consist ofindividual permanent magnets or of permanent magnets which have on oneside or on both sides pole shoes made of a soft-magnetic material.Advantageously, the magnet ring can also be made of a single piece—forexample, as a pressed, injection-molded or sintered ring, which can thenbe magnetized in sectors with alternating pole orientation. The axial,radial or axial-radial pole orientation, when arranged between othersoft-magnetic flux elements, supports the axial-radial path of the fieldlines desired in the energy converter around and through the flat coil.On the other hand, such field line path can be readily achieved withcompletely through-magnetized permanent magnets, i.e., magnets which aremagnetized through the entire volume from one surface to the othersurface. Accordingly, very short field line paths can be realized withthis design of the permanent magnets, as well as a high volumeefficiency and material utilization of the permanent magnets.

The energy converter of claim 1 includes magnetic flux elements whichare implemented as toothed elements and which form a soft-magnetictoothed element ring, which is rotationally symmetric and concentricallyarranged relative to the rotation axis of the rotor. This toothedelement ring is also a component of the rotor.

So called toothed element gaps, i.e., regions without the soft-magneticmaterial, are disposed between the toothed elements. The magnet ring andthe toothed element ring are arranged coaxially and separated from eachother only by a narrow annular air gap. Depending on the position of thetoothed elements, the field lines emanating from the permanent magnets,aside from unavoidable parasitic magnetic flux returns caused by thedesign, close essentially via two paths. A short path runs via toothedelements, adjacent permanent magnet elements and from there via magneticflux elements acting as flux return. In addition, a long path exists viathe large axially-radially oriented magnet circuits, which extend viathe toothed elements and additional magnetic flux elements through thecenter of the flat coil. The toothed element gaps are important forguiding the magnetic flux via the toothed elements through the coilcenter and to prevent premature return flux. The requirement forsufficiently large toothed element gaps is one of the major obstaclespreventing miniaturization. Only field lines which are guided around thecoil in an axially-radially oriented magnet circuit are relevant for aneffective electromagnetic coupling of permanent magnets and flat coiland hence for energy conversion. If a toothed element directly faces apermanent magnet element, then the magnetic flux via the long path,i.e., in the axially-radially oriented magnetic circuit through the flatcoil is maximal. Conversely, if a toothed element is located between twopermanent magnet elements, then the short path is maximally utilized andthe flux through the flat coil is zero.

The flux in a magnetic circuit depends on the shape of the magneticcircuit, i.e., also on the relative position of its magnetic fluxelements and is connected in the event of a changing reluctance with acorresponding force between the magnetic flux elements. By arranging thetoothed element ring according to claim 1 so as to be connected with therotor and therefore movable, the flux in the large axially-radiallyoriented magnetic circuits extending through the flat coil can bechanged by rotating the rotor, which makes it practical to convertmechanical energy via magnetic energy into electric energy and viceversa. If the number of the toothed elements is identical to that of thepole pairs of the magnet ring, if the toothed elements and the permanentmagnet elements are uniformly distributed about the circumference, thenthe axially-radially oriented magnet circuits always have a maximaltotal flux in the same direction if the toothed elements and thepermanent magnet elements have a frontal position. Accordingly, amaximal magnetic flux of all permanent magnets can alternatingly beconducted through the flat coil during rotation, first with one poleorientation and then with the other pole orientation. Movement of therotor then produces maximal gradients in the magnetic flux changethrough the flat coil for mechanical-electrical energy conversion. Foran electromechanical energy conversion, the combined flux of the coilcauses a field displacement and therefore a torque on the rotor.

The annular air gap between the magnet ring and the toothed elementsaccording to claim 1 can be arranged very tightly because of the radial,axial or axial-radial arrangement. This results in very advantageousoperating points for the permanent magnets, thus satisfying an importantprerequisite for effective energy conversion at low rotation speeds.

The different preferred path of the magnetic field lines, which dependson the relative position of the toothed element to the permanent magnetelement, i.e., via the short path or via the long axial-radial path,causes a latching torque in corresponding rotor positions. The width andshape of the toothed element can be optimized so that the correspondingforces have an opposing effect on a torque and thereby affect, i.e.,minimize, the individual latching torques as well as the total latchingtorque. In particular, the latching torques as well as possibly also thestray flux can be reduced by providing the toothed elements with acurved shape, such as a sickle shape.

It is advantageous for the efficiency of the energy converter if thecore zone is as small as possible, i.e., the flat coil has the smallestpossible inside diameter for receiving a large number of low-resistancewindings. Moreover, the magnet ring should have the greatest possibleinside diameter for accommodating the largest possible effective magnetcross-section, and for also realizing a large pole number, for achievinga high circumferential velocity at the circumference of the rotor toeffect large magnetic flux changes, and for minimizing parasiticmagnetic return flux due to the limited space. In addition, for a largedistance between the core zone and the peripheral annular air gap, thegaps between the toothed elements can be larger or extend deeper towardthe center to minimize magnetic stray flux. According to claim 1, alarge outside diameter of the magnet ring can be easily realized byarranging the annular air gap between the toothed element ring and themagnet ring in a peripheral region outside the core zone. This appliesalso to other energy converters, for example the tachometer generatordisclosed in DE 2560231 C2.

Advantageously, claim 1 also makes it possible to realize flat coilswith a small inside diameter. Generally, at least two annular air gapsare required for energy converters of the aforedescribed type, so that arotor can move freely in the stationary section of the energy converter.Claim 1 allows the following two basic design alternatives: a core zonewith an annular air gap, or a core zone without an annular air gap. Inthe first case, both annular air gaps are arranged outside the core zoneand a corresponding magnetic flux element which is part of the rotordisk encloses the flat coil from the interior through the core zone. Thediameter of this magnetic flux element can be minimized s that themagnetic flux remains below saturation. The inside diameter of a flatcoil can be designed accordingly. In the second case, a discontinuity,namely the annular air gap, is located in the core zone between rotorand stationary magnetic flux elements. In this case, the rotor must beguided or supported in addition to the magnetic flux. If several annularair gaps are located in the core zone, then according to claim 1, atleast one annular air gap must be arranged axially between the rotordisk and a stationary magnetic flux element. The annular air gap canalso be a separately constructed section of a larger annular air gapconsisting, for example, of a radial section and an axial section. Thisaxial annular air gap can directly conduct the magnetic flux between therotor disk and the stationary magnetic flux element. This occursexclusively in a region outside the rotor shaft when using anon-magnetic rotor shaft. Because the cross-sectional area of aconventional rotor shaft is small compared to the area of the air gapbetween the rotor and the stationary magnetic flux element, the magneticflux would be preferably conducted via the axial annular air gap and notvia the existing design-related radial annular air gap, oven withsoft-magnetic rotor shafts. A bearing according to claim 2 can be easilyintegrated in the design by employing the axial annular air gap.Combining the magnetic flux conduction with the bearing function resultsin a space-saving design, which is important for miniaturization. Axialannular air gaps generally offer optimal choices for selecting materialsand design dimensions, so that all support, guiding and magnetic fluxfunctionalities can be realized within the core zone and the core zoneitself can be minimized. This enables flat coils with a small insidediameter and therefore a high energy conversion density. A bearing thatfills additional space is not yet integrated in DE 25 60 231 C1, and thefield lines are guided preferably or exclusively by a radial air gapdisposed between the rotor and the stationary magnetic flux elements.Magnetic saturation can easily occur for the small rotor shaft diametersnecessitated by miniaturized designs. This shortcoming can only beovercome with a relatively strong rotor shaft, which has disadvantagesfor the operating characteristics, or with an initially reduced magneticfield energy, which has disadvantages for the energy conversion density.In addition, bearing support has to be provided as well as asufficiently large air gap area for an adequate magnetic flux. Thelatter is possible only with a correspondingly large rotor shaftdiameter and also a long radial annular air gap. This uses up more spaceand causes a larger friction torque due to the large bearing surfaces,if the bearing of the rotor is integrated in the converter. A radial airgap design, which implements these bearing and magnetic fluxfunctionalities, requires more space in the core zone than an axial airgap design. Coils with a radial air gap design therefore have a largerinside diameter and a smaller power density and efficiency. An energyconverter with a radial annular air gap in the core zone is hence notamenable to miniaturization. An axial annular air gap in the core zoneaccording to claim 1 is more compatible with a flat energy converter,both constructively and functionally, than a radial annular air gap, andbetter takes advantage of a flat design for a high energy conversiondensity. Axial annular air gaps for energy converters with an annularair gap in the core zone or a design which moves air gaps away from thecore zone enable a more compact design with a smaller core zonediameter, which results in higher power densities even when the energyconverters are miniaturized. This is a particular advantage over energyconverters with a radial annular air gap, such as the tachometergenerator described in DE 25 60 231 C1. The latter is primarily intendedfor measurement tasks, where high power densities are secondary and thetachometer generator arrangement can be supported via the motor shaft.

Another significant increase in the efficiency can be achieved with anarrangement according to claim 3. Magnetic flux and bearing functionscan advantageously be combined by arranging a layer of a hard materialbetween the soft-magnetic parts of the rotor and the stationary magneticflux element which supports the rotor. Advantageously, a friction layermade of a hard material is arranged in the region of the axial annularair gap. Because sliding layers made of a hard material have layerthicknesses of only several micrometers or less, very narrow annular airgaps can be realized, so that the axially-radially oriented magneticcircuits are only insignificantly attenuated at that location. Thesliding layer made of the hard material can be applied on the rotorside, on the stationary magnetic flux element, or on both bearing sides.Advantageously, the hard material for the friction layer can be carbonin the form of diamond or with a lattice structures similar to thatdiamond, which can be deposited, for example, from the gas phase by aPVD process. The bearing should not only have a low frictioncoefficient, but also a low wear rate and high temperature stability.Advantageous is also a hard layer made of iron, for example, byembedding foreign atoms or through another change in the atomic ironlattice structure, which can produce a zero air gap. Overall, a bearingdesign according to claim 3 significantly increases the efficiencycompared to other solutions that form additional air gaps.Advantageously, the energy converter is also simple, robust, reliable,and has a small size.

The efficiency can be further improved by constructing the flat coilsaccording to claim 4. A very high fill factor of the coil winding can beachieved with helical coils arranged in a single plane and by usingmetal tape as the conducting material, which is particularly effectivewith flat coils. Suitably wound flat coils have a higher mechanicalstability compared to coils wound with round wire, are easier toinstall, have a higher inductance with a smaller ohmic resistance, andrealize a higher energy conversion per unit volume with lower losses.

Energy converters according to claims 1 to 4 can be easily andadvantageously upgraded or combined. For example, according to claim 5,a rotor or certain rotor regions can be utilized by two energy converterunits constructed according to claim 1 to 4. This can advantageouslyresult in less material-consumption, improved compensation of magneticforces or reduction of the bearing forces as well as improved operationof the energy converters.

With a suitable design of the toothed elements, energy convertersaccording to claim 6 can be operated as self-starting synchronousmotors. The preferred rotation direction can be defined, for example, byforming bevels or sickle-shaped projections on the toothed elementheads. The energy converter can be designed and the flat coil can becontrolled so as to provide a motor function with a single energyconverter according to claim 6. However, the rotation direction can bebetter controlled by using two energy converters coupled via the rotors,which also improves and simplifies the control, start-up and runningcharacteristics. The two energy converters can be coupled either byaxially connecting the two energy converters according to claim 5 or bya forced coupling, for example a gear mechanism, according to claim 7.Finally, coupling of the energy converters can also affect the totallatching torque, which can potentially be reduced by the design of theenergy converter recited in claims 1 to 7.

Energy converters according to claims 1 to 7 are simple, robust,reliable and cost-effective. Nearly all components of electromechanicalenergy converter according to claims 1 to 7 can be a part of the energyconversion process, while stationary magnetic flux elements can alsoperform other functionalities, such as bearing or housingfunctionalitics. Because of this and the basic design of claim 1, theenergy converter has a high energy conversion density per unit volume.The energy converter can be manufactured using conventionalmanufacturing techniques, and even small devices with a high powerdensity can be readily realized.

The invention will be described hereinafter in more detail withreference to an embodiment.

The drawings show in:

FIG. 1 an energy converter with axially oriented permanent magnetelements;

FIG. 2 a cross-section of the energy converter of FIG. 1 taken along theline A-A;

FIG. 3 an energy converter with radially oriented permanent magnetelements;

FIG. 4 a cross-section of the energy converter of FIG. 3 taken along theline B-B (detail);

FIG. 5 an energy converter with radially oriented permanent magnetelements and pole shoes;

FIG. 6 a cross-section of the energy converter of FIG. 5 taken along theline C-C (detail);

FIG. 7 an energy converter with curved permanent magnet elements;

FIG. 8 energy converters, coupled via a common rotor;

FIG. 9 an energy converter with a basket-shaped toothed element wheel;

FIG. 10 an energy converter, with a geared coupling; and

FIG. 11 a top view of the energy converter of FIG. 3 with sickle-shapedextensions on the toothed elements (detail).

As shown in FIG. 1, the electromechanical energy converter according toclaim 1 includes a rotor shaft 3 made of polished sapphire, which isdisposed in a center holed pin 1 of a punched disk 2 so as to be freelyrotatable about its rotation axis 4. A rotor disk 5 is made of siliconiron and fixedly connected with the rotor shaft 3. A toothed elementring 6 is securely mounted on the outer periphery of the rotor disk 5.The toothed element ring 6 is constructed of four respective ringsectors made of a metal-metal-composite, such as silicon iron and brass.The iron ring sectors form the toothed elements 7 and the brass ringsectors form four toothed element gaps 8 according to claim 1. Sincethere is no gap between the soft-magnetic rotor disk 5 and thesoft-magnetic toothed elements 7 of the toothed element ring 6, therotor disk 5 and the toothed element ring 6 form constructively andmagnetically a unit, referred to as a toothed element wheel 9. Thetoothed element wheel 9 and the shaft 3 form a rotor 10. A flat coil 11is placed directly around the holed pin 1 between the disk-shapedportion of the punched disk 2 and the toothed element wheel 9. The corezone 12 of the energy converter is indicated by two dashed boundarylines and is by definition according to claim 1 bounded by the insidediameter of the flat coil 11. A magnet ring 13 made of the magneticmaterial neodymium-iron-boron embedded in plastic is arranged verytightly about this flat coil 11, also between the disk-shaped portion ofthe punched disk 2 and the toothed element wheel 9. The magnet ring 13is magnetized axially in alternating directions and can therefore beviewed as consisting of eight individual permanent magnet elements 14.The flat coil 11 and the magnet ring 13 are firmly glued to the puncheddisk 2. A housing enclosure 15 is tightly placed on the periphery of thepunched disk 2 and secured with an adhesive, thereby also sealing offthe entire arrangement on the backside of the toothed element wheel 9and protecting it from outside contamination. The interior center of thefront face of the housing enclosure 15 also functions as an additionalaxial bearing for the rotor shaft 3. A sliding bearing 16, consisting ofsintered bronze and operating as a radial and axial bearing, is disposedinside the holed pin 1. All parts are arranged rotationally symmetricabout the rotation axis 4, which represents also a system axis for theentire electromechanical energy converter. The protruding, magneticallyinactive sliding bearing 16 forms on the font side of the punched disk 2between the rotor disk 5 and the holed pin 1 an axial annular air gap 17of approximately 0.05 mm, which transmits practically the entiremagnetic flux in the core zone 12. Separation of the bearing andmagnetic flux function in the core zone 12 guarantees, on one hand, areliable bearing operation and, on the other hand, a well defined andreproducible magnetic flux in the core zone 12. An additional 0.1 mmwide annular air gap 18 is disposed between the toothed elements 7 andthe magnet ring 13. The punched disk 2, the permanent magnet elements14, the toothed element wheel 9 as well as the annular air gaps 17 and18 form, when the toothed elements 7 and permanent magnet elements 14are in a frontal position, the axially-radially oriented magneticcircuits 19 with magnetic field lines 20 that extend tightly around orthrough the flat coil 11 in an axial-radial direction. The annular airgaps 17 and 18 represent magnetic resistances in the axial-radialoriented magnetic circuits 19, which is necessary to ensure the functionof the electromagnetic converter according to claim 1. When the rotor 10rotates, all toothed elements 7 move past the permanent magnet elements14 of one pole orientation and then past the permanent magnet elements14 of the opposite pole orientation. FIG. 1 illustrates a situationwhere the permanent magnet elements 14 and the toothed elements 7 arepositioned so as to directly face each other. The preferred path of themagnetic field lines 20 extends via the long paths along theaxially-radially oriented magnetic circuits 19 with substantiallyseparate axial-radial field line paths for each permanent magnet element14 around and through the flat coil 11.

FIG. 2 is a top view of the same energy converter as FIG. 1. However,FIG. 2 shows the intermediate position of toothed elements 7 relative tothe permanent magnet elements 14, where the magnetic field lines 20 areclosed preferably by the short path via the toothed elements 7 to thecorresponding adjacent permanent magnet element 14 and from there via arearward magnetic flux element 21, in this case the punched disk 2, backto the original permanent magnet element 14. The mechanical energy istransmitted to the environment via the pinion 22, whereas the electricalenergy is transmitted via two wire ends 23 of the coil.

The magnetic field lines 20 in the energy converters of FIGS. 1 and 2pass through the annular air gap 18 between the magnet ring 13 and thetoothed element ring 6 in the axial direction. A, different energyconverter according to claim 1 is shown in FIG. 3, where the permanentmagnet elements 14 are arranged so that the magnetic field lines 20emerge in the radial direction and reach the toothed element ring 6 viathe annual air gap 18. The magnet ring 13 is composed of individualpermanent magnet elements 14 in the form of small cuboids which areglued directly on the interior wall of a cup-shaped punched disk 2 witha spacing of half the width of a cuboid. The permanent magnet elements14 are made of the Samarium-Cobalt cuboids and represent individualmagnets 24. The toothed element gaps in the embodiment of FIG. 3 aredirectly milled into the soft-magnetic rotor disk 5 and consequently arecomposed of air. The toothed elements 7 are formed simultaneously, sothat the toothed element ring 6 and the rotor disk form a unitarycomponent. According to FIG. 3, a several micrometer thick sliding layer25 made of a hard material is applied to the holed pin 1 of the puncheddisk 2. The sliding layer 25 is applied on both sides of the end facesand also inside the holed pin 1. The spacing between the toothed elementwheel 9 and the pinion 22, which are both fixedly secured on the rotorshaft 3, are only approximately 5 μm greater than the length of theholed pin 1, including the hard coating. An identical spacing existsbetween the rotor shaft 3 and the interior hole in the holed pin J. Thisarrangement provides a very stable axial and radial sliding bearing, aswell as an axial annular air gap 17 of less than 10 μm. Theaxially-radially oriented magnetic circuits 19 are then only slightlyweakened at this location by a very small magnetic resistance. Thearrangement illustrated in FIG. 3 has the advantage that the flat coil11 can fill the entire region between the toothed element wheel 9 andthe punched disk 2, while due to its radial position, a very narrowannular air gap 18 between the permanent magnet elements 14 and thetoothed elements 7 can be designed and fabricated. The core zone 12 canalso have a very small diameter, because the holed pin 1 can be usedeffectively both as a magnetic flux element 21 and as an element for thesliding bearing. Because the holed pin 1 has three times the diameter ofthe rotor shaft 3, which corresponds nine times the area, a radial airgap in the core zone 12 would likewise have less of an effect onmagnetic flux guiding when a soft-magnetic magnetic shaft 3 is used. Forincreasing the inductance, the flat coil 111 in the arrangement of FIG.3, corresponding to claim 4, is made of a helical coil wound in a singleplane, wherein a varnish-coated metal band with dimensions 1.2×0.02 mmis used as coil material.

FIG. 4 shows a top view of the arrangement of FIG. 3, with the toothedelements 7 and permanent magnetic elements 14 shown in the intermediateposition, like in FIG. 2. The energy converters of FIGS. 1-4 have adiameter of 12 mm and a height of 3 mm.

FIG. 5 shows an energy converter with a magnetic pole orientationsimilar to that of FIGS. 3 and 4, except that both functionally requiredannular gaps 16 are located outside the core zone 12, and no annular gap16 is located inside the core zone 12. The magnet ring 13 is made hereof a composite of brass segments 26 and separated soft iron segments,with individual magnets 24 arranged between the soft iron segments. Thesoft iron segments represent pole shoes 27 for the individual magnets 24and form in conjunction with the individual magnets 24 the permanentmagnet elements 14. The toothed element ring 6 is composed of anassembly of the elements 7 made of soft iron and toothed element gaps 8made of brass. The toothed element ring 6 is welded on a rotor disk 5made of brass to form a cup-shaped assembly. The flat coil 11 is almostcompletely surrounded by a soft magnetic, two-part coil core 28, whichrepresents a stationary magnetic-flux element 21. The magnet ring 13 andthe toothed element ring 6 engaging from above are located in theopening of flux element 21. In this arrangement, the two radial annularair gaps 16 are located between the toothed elements 7 and the magnetring 13 and also between the toothed elements 7 and the coil core 28.Because the coil core 28, the toothed element ring 6 and the magnet ring13 can be manufactured as turned parts, very narrow, several μm wideradial annular air gaps can be realized. This is not possible with thearrangement of FIGS. 3 and 4 due to the planar design of the individualmagnets 24.

FIG. 6 shows a top view and an intermediate position of the arrangementof FIG. 5, where the magnetic field lines 20 are closed along the shortpath.

FIG. 7 shows another arrangement, where only the annular gaps 16 arelocated outside the core zone 12. In addition, curved permanent magnetelements 14 are used, which are magnetized along their curved sectionand are combined to a magnet ring 13 with alternating pole sequence.With the magnetization extending along the curved section, both amagnetic North Pole and magnetic South Pole projects in the radialdirection towards the center of the energy converter at different axialpositions. Two soft magnetic rotor disks 5 are pressed onto a rotorshaft 3 in abutting relationship and together form the rotor 10. Atoothed element ring 6 is machined out of the rotor disks 5, like inFIGS. 3 and 4. A free space for the self-supporting flat coil 11 whichis glued to the magnet ring 13 is provided inside the rotor 10. Thecurved permanent magnetic elements 14 and rotor disks 5 form theaxially-radially oriented magnetic circuits 19 which according to claim1 enclose the flat coil 11 through its coil center. Very small radialannular air gaps 16 can likewise be set with the arrangement of FIG. 7.

FIG. 8 shows an arrangement according to claim 5, wherein two energyconverters similar to those of FIGS. 1 and 2 have a common rotor 10 witha common toothed element ring 6 and a common rotor disk 5. Thisarrangement has to advantage that in particular axial forces can becompensated.

The energy converter in FIG. 9 corresponds to the energy converter inFIG. 3, except that the toothed elements 7 are here angled with respectto the rotor disk 5. The toothed element wheel 9 is then in the shape ofa basket, with the permanent magnet elements 14 and the toothed elements7 being able to face each other along the annular air gap 18 over alarger area. Such an arrangement also results in a high energyconversion density, when permanent magnetic materials with a lowresidual induction are used, such as permanent magnets in a plasticbinder.

FIG. 10 shows a geared drive according to claim 5 between two energyconverters 9 of the type depicted In FIGS. 3 and 4, which are coupledvia a coupling gearwheel 30. The rotational and hence also themechanical energy are transmitted by the coupling gearwheel 30 via adriveshaft 31 to the outside. Both energy converters are received in acommon housing 32 which also supports the driveshaft 31. By arrangingthe toothed elements 7 in one energy converter 29 so as to face thepermanent magnets 14 directly, whereas the toothed elements 7 and thepermanent magnetic elements 14 in the other energy converter 29 assumean intermediate position, the motor can operate with a controlledrotation direction by sending a current alternatingly through therespective flat coils 11 of the energy converters 29.

FIG. 11 shows an alternative exemplary embodiment of the toothedelements 7 depicted in FIG. 3 for defining the start-up direction of theenergy converter in motor operation. The different magnetic saturationin the sickle-shaped projection 33 under different current flows throughthe flat coil 11 defines the start-up direction. Alternatively,following the same principle, the start-up direction can also be definedby differently shaped, asymmetric chamfers, steps or segments in form ofspiral sections.

1. Electromechanical energy converter with a rotor (10), wherein a stationary flat coil (11) is arranged concentrically about the rotation axis (4) of the rotor (10), the region inside the axial projection zone of the inside diameter of the flat coil is defined as a core zone (12), stationary permanent magnet elements (14) arranged with rotational symmetry and having an alternating pole orientation in axial, radial or axial-radial direction form a magnet ring (13), magnet flux elements (21) are shaped as toothed elements (7), the toothed elements, which are arranged with rotational symmetry and are separated from each other by toothed element gaps (8), form a soft-magnetic toothed element ring (6), the number of the toothed elements (7) is identical to the number of the pole pairs of the magnet ring (13), the toothed elements (7) and the permanent magnet elements (14) are uniformly distributed along the periphery, the toothed element ring (6) is a component of the rotor (10), at least one annular air gap (18) exists outside the core zone (12) between the magnet ring (13) and the toothed elements (7), an annular air gap (17) disposed inside the core zone (12) is arranged axially between the rotor (10) and a stationary magnet flux element (21), and the permanent magnet elements (14), the toothed elements (7) as well as additional magnetic flux elements (21) and at least two annular air gaps (17, 18) together form axially-radially oriented magnetic circuits (19), which extend axially-radially around the flat coil (11) through its coil center and surround the flat coil (11).
 2. Electromechanical energy converter according to claim 1, characterized in that a stationary soft-magnetic magnetic flux element (21) includes a bearing function for the rotor (10).
 3. Electromechanical energy converter according to claim 2, characterized in that a sliding layer (25) made from a hard material is disposed between the stationary soft-magnetic flux element (21) having the bearing function and the rotor (10).
 4. Electromechanical energy converter according to claim 1, characterized in that the flat coil (11) comprises one or more single-plane helical coils, with a metal strip as a conducting material.
 5. Electromechanical energy converter according to claim 1, characterized in that a common rotor (10) is used for two axially superimposed energy converters (29).
 6. Electromechanical energy converter according to claim 1 characterized in that the geometric shape of the toothed elements (7) is designed for defining a preferred rotation direction of the energy converter (29).
 7. Electromechanical energy converter according to claim 1, characterized in that the rotor (10) of the electromechanical energy converter (29) and the rotor (10) of an additional electromechanical energy converter (29) according to one of the preceding claims are coupled via a coupling gear wheel (30) or via a different forced coupling.
 8. Electromechanical energy converter according to claim 1, characterized in that the toothed elements have a curved shape. 